Error in compiled file but not in IDE

I am not sure why I am getting this error. I have a program written 4 or 5  
years ago compiled many times over the years as well as in LW 6.0 running  
W7 64bit... that used to work fine in both the IDE as well as compiled.  
Now it works fine in the IDE but not after it is compiled. The compiled  
program reports the follow error, when I try to execute it:

Invalidate structure-superclasses <and a simple test case, if possible>


I'm on W7 64bit, with LW 6.1.0.

Any idea what's wrong?


Thanks,

William